Self-locking devices for locking various members together and subsequently unlocking them have been known and used for many years and there are many commercially successful self-locking devices which are currently available on the open market. However, there is always a need and a desire to make these self-locking devices simpler and easier to operate, as well as more economical to manufacture and to maintain in service and use. Also, there is always a need and a desire to make these self-locking devices more automatic and self-actuating in their operation and more foolproof and tamper-proof in their service and use.